1. Field Of The Invention
The present invention relates to integrated circuit technology. More particularly, the present invention relates to object recognition and an integrated circuit system for recognition and identification of moving objects.
2. The Prior Art
Simple object recognition is a relatively easy task if the position of the object and its velocity are known. In this case, a registered, stationary image of the object can be obtained typically by using a linear array of photosensors. The captured image can then be fed to an object classifier circuit for analysis.
Image motion can be caused by an object moving past a stationary imaging device, by an imaging device moving past a stationary object, or by a combination of both. If the image velocity is unknown, then the object recognition process cannot rely on a priori knowledge of position and velocity. For example, when the object motion is caused by a conveyor belt upon which the object is moving or the hand of a person holding the object to be recognized or when an object, whose velocity is impossible to measure, passes in front of the recognizer, its velocity may not be readily determinable. In such instances, object recognition becomes a much more difficult problem.
Furthermore, in some instances the object's velocity may be high enough for the image to move several pixels during the frame time of a standard CCD imager. If this is the case, the image of the object captured on a such an imager retina is corrupted and distorted by motion "smear" in the retinal image plane.
First consider an object moving approximately in the x direction at an unknown velocity. The image of that object is the two-dimensional projection of an object out of a set of objects that we wish to recognize, for example, parts on a conveyor belt or alphanumeric characters, whose y location is within a predetermined range, but its precise location within that range is not known. The task of an apparatus for recognizing moving objects is to assign each object either to one of a number of predetermined classes to which it is the best match, or to declare the object unrecognized if there is not enough of a match with any of the classes.
To perform such a classification by standard methods would require an area imager with a sufficient number of pixels in the x and y directions to respectively cover the maximum width of the object at the required resolution, and the maximum height of the object plus whatever range of uncertainty in the y position is required by the application. Furthermore, the imager would need to be fast enough to scan out the complete image in a time shorter than that required by the image of the object--moving at maximum speed--to travel a fraction of a pixel in either the x or y direction. In imagers operating at slower scanning speeds, the object will appear distorted; the amount of the distortion being proportional to the velocity of the object.
In addition to an imager,two frame buffers to store the image would be required; one being used for the object recognition process while the other is being loaded. If the velocity of the image is sufficiently low, one frame buffer may be enough: the image will be first loaded and then operated upon, and the cycle will repeat.
Finally, a microprocessor and related software are needed to perform the recognition operations on the data stored in the frame buffer.
The above-described method works as long as the number of frames to be processed is less than approximately 50 per second. This limitation imposes severe restrictions on the speed of the image and/or the knowledge of the position of the object.
If the velocity of the object is high, for example, traversing the width of the imager in 10 msec or less, and nothing is known about the y position of the object (other than being within the range of the imager), the demands on the electronics are very large and cannot be accommodated by conventional methods and components. In this case, a higher level of parallelism is required.
It is an object of the present invention to provide a single integrated circuit for recognizing objects in a moving image when neither the object's velocity nor the position are known with sufficient accuracy.